The invention relates generally to welding systems, and more particularly to a welding system designed to push and pull welding wire fed by a wire feeder.
A wide range of welding systems are known and are currently in use. These include stick welding systems and inert gas welding systems, and particularly, of the latter type, metal inert gas (MIG) welding systems. In MIG welding systems wire is fed from a spool through a welding cable to a welding torch. In many systems of this type the wire may be pushed through a welding cable and the torch via a drive motor in the wire feeder. The wire feeder itself may be packaged in a welding power supply, or may be in a separate enclosure coupled to the power supply. The wire is fed through the torch and is consumed as welding progresses, the metal of the wire forming part of the weld bead. In many such systems, gas is also fed through the torch to shield the weld pool, although the systems may also be adapted for gasless welding, such as through the use of self-shielded flux-cored wire.
In some systems of this type, drive motors and mechanisms in the wire feeder may not be sufficient or appropriate for the type of wire used. For example, aluminum wire typically cannot withstand the same degree of column loading as steel wire. Accordingly, systems have been developed to pull such wire through the welding torch, imparting a tensile load on the wire rather than or in addition to a compressive load from a motor in the wire feeder. Systems have also been developed to both push and pull the wire. These often require precise coordination of the drive motors that push and pull the wire to avoid either placing the wire between the motors under excessive tensile or compressive loads. Particularly troubling are compressive loads that may cause the wire to bunch or bend within the welding cable. Such malfunctions may require time consuming disassembly of the system to extract the wire and to re-feed it before welding can continue. Other issues exist with excessive pull or tensile forces insomuch as metal shavings from the welding wire can accumulate and cause problems with later operation.
Improved systems are therefore needed for feeding wire through welding systems to welding applications. There is, in particular, a need for systems that can allow for accurate speed control of the wire, while avoiding bunching or bending of the wire between push and pull drives.